Why wasn't the java.lang.Object class declared to be abstract ?
Surely for an Object to be useful it needs added state or behaviour, an Object class is an abstraction, and as such ... |
I am looking for a way to do the following:
A Project :
Defines an abstract class that is called when some events happen (event handler if you will)
Defines the engine that will ... |
this is the code:
import java.awt.*;
import java.applet.*;
public class anim1 extends Applet{
public void paint (Graphics g)
{
g.drawString("",400,300);
...
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I'm trying to determine if a generic class object is an instance of an abstract class. So far I'm not having much luck. Below is the code I'm trying ... |
I am trying to use template design pattern so I use abstract class to define my algorithm like this:
abstract class MyTemplate
{
public void execute()
{
...
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While writing UI automation tests I come across forms with many fields and instead of passing numerous arguments to test methods I create classes to quickly set form data. So if ... |
hi everyone, i am writing a java application that needs to interface with an api that is poorly documented. i need to retreive parameters from the contents of a List but the documentation does not specify what these objects are. i've written the following code to work out what they are: Iterator i = databaseParameters.iterator(); while(i.hasNext()){ Object curr = i.next(); log.debug("Classname ... |
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There are cases where you want to create an instance of a basic class for uses such as tagging, locking, keying and the like. While you could just as easily write an empty class that extends Object and provides nothing else, it provides nothing more or less than the Object class itself. While I kind of agree that it could be ... |
Peter, Thanks for reply. Here is what I understood from the solutions given by you: 1. Object o=new Object(); synchronized(o) { } Does it make sense? I am creating an object and covering it with Sync block. Its as good as not having sync block because I am taking a lock on the different object and may be in sync block, ... |
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Hi Vinod, in an abstract class you can define an interface (method declarations) and optionally some behavior that's already known. But you want to say explicitly with the abstract concept that the class in question is not complete and therefore no objects can be created directly from it. Therefore child classes have to fill in the missing parts and then you ... |
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public abstract class Vehicle { private double regoCost; private int regoNumber; private int yearManufactured; private int currentYear = 2010; public Vehicle(int yearManufactured, int regoNumber) { this.yearManufactured = yearManufactured; this.regoNumber = regoNumber; } public boolean regoCheck() { int vehicleAge = this.yearManufactured - currentYear; if (vehicleAge > 4) { return true; } else { return false; } } public void setRegoCost(double regoCost) { ... |
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Abstract class 1) it may not have abstract methods then extend the class .you can create the instance of the derived class referred by abstract class reference variable 2) it may contain abstract methods then derived class must implement the abstract methods then you can create the instance of the derived class referred by abstract class reference variable |
No. But what are different method in Object class, we generally do not override and also we rarely make the instance of the Object class. In that way, this can be created as abstract class, but for some reason it is made as concrete class. What are these deciding factors which make Object class as concrete??? |